LED vs. LCD: Which is better?

By Ty Pendlebury and Philip Wong on 01 July 2009

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You're walking through your local electronics store looking for a new TV, and you come across a thing called an "LED TV". Which then leads you to ask: "Is that the same technology they use for the giant screens at football games?" And the answer, quite simply, is no.

While the giant Mitsubishi screen at Melbourne's MCG, for example, is made up of thousands of LEDs that are used to directly produce a picture, Samsung's "LED" TVs are actually LCDs. That's right, they're not LED TVs at all. Confused?

Samsung's televisions use a series of LEDs to light up the panel, and it's not the only company that does this. But what is backlighting anyway?

Why do LCD screens need a backlight?

As a consumer technology, LCD has been in widespread use since the early 70's where it first appeared in digital watches. As its name suggests, Liquid Crystal Display is a liquid which has been sandwiched between two plates, and it changes when a current is applied to it.

While we've had black-and-white LCDs for years, colour LCDs are a lot more recent, but the technology is the same. As we all know, you need to press a button to read a watch in the dark, and an LCD TV is no different. It needs a light behind it because it emits no light of its own.

A selection of LCD screens, including Samsung's 6 and 7 series, showing the differences between backlighting technologies. The screen on the right features a fluorescent tube backlight. (Credit: CNET Asia)

What types of backlights are there?

At present there are two main methods of backlighting in LCD flat-panels: Cold-Cathode Fluorescent Lamp (CCFL) and LED (light-emitting diode). There are several others, and this includes Sony's Hot Cathode Fluorescent Lamp (HCFL), but only one television currently uses this method.

CCFL is the most widespread method of backlighting for LCD televisions, and consists of a series of tubes laid horizontally down the screen.

A cutaway of a CCFL-backlit LCD showing the different layers of polarisers and filters, and the thin fluorescent tubes themselves (right).(Credit: Ty Pendlebury)

LED backlighting is still relatively rare, but has been in use in televisions since 2004 when it first appeared on a Sony WEGA television. Though there are several different ways of backlighting using LEDs (as we'll explain shortly), the idea is the same: a lot of LED bulbs are used to light the screen.

Direct or edge mounted?

There are two different methods of LED backlighting: direct and edge. The main advantage of direct lighting is that it can be used to increase contrast levels by turning some LEDs off — thus increasing the amount of black in parts of the picture. LG is one of the champions of direct-lighting.

In comparison, edge-lighting's main advantage is that it can be used to make screens that are incredibly thin — the LEDs are at the side and not behind the screen. Of course, you lose the ability to switch off parts of the backlighting for better contrast, and picture quality could also suffer if light isn't sufficiently well dispersed.

White or RGB light?

White LED is very similar to CCFL because it uses a blue light source that is made to look white by the presence of a sulphur coating on the bulb. As a result, the television will potentially be stronger in the green portion of the spectrum, but as some CCFL technologies enable better red and blue response, better white LEDs could also be possible. The Samsung UA40B7100 is an example of a TV that uses White LEDs.

An edge-mounted, white LED module (Credit: Ty Pendlebury)

RGB LEDs, on the other hand, are potentially capable of a broader colour range because they use three LEDs coloured red, blue and green. Its proponents argue there is less of a green "push" as a result and the colour spectrum is more evenly distributed. The Sony Bravia KDL-46XBR45 is an example of a television that uses RGB LEDs in its backlight.

An RGB backlight(Credit: Samsung)

Samsung's technology under the microscope

The Korean company's edge-lit LED-backlit unit comprises of two major components: a long LED module with a row of tiny white diodes and a thin screen-sized plastic sheet known as a light guide plate. Four LED modules are deployed along the left, right, top and bottom of the panel. The combined light output is then funnelled and redistributed evenly across the screen.

Essentially, the edge-lit LED system lacks fine backlight control compared with its predecessor. To put this into perspective, a Samsung series 9 panel can turn on selected LEDs to bring out the sparkle of stars in a galaxy, while switching off the remaining bulbs to produce deep blacks for the background. In the case of the new LED TVs, the lumens are set at screen level, so there's a contrast trade-off when rendering scenes with both bright and dark portions.

Samsung's edge-lit screen requires a light-guide, which is used to distribute light across the screen. (Credit: CNET Asia)

Is the price premium for LED worth paying?

We find it interesting that TV manufacturers are currently asking a higher asking price for LED-backlighting when many cheap devices — particularly mobile phones and netbooks — use LEDs as backlights. According to Samsung, LED backlights currently cost three times more in large sizes than the equivalent CCFL arrangement, and this is mostly due to a lower number of manufacturers. Presumably, when the technology begins to take a firmer hold the price will come down due to increased competition.

The few LED-backlit screens we've seen have been very good, and while we personally prefer plasma, the combination of thin design and sharp picture quality will find favour with many people. If you're looking for a further explanation of how LCD screens work, then you can try this video on the 3M site.

Topics: tv, samsung, led, home theatre, hdtv, backlit, led tv, sony, direct, edge

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Comments (8)

  • Jason Zhou commented on 15/10/2009 10:34 Report abuse

    Re:LED tube(SMD) T5 and T8
    Dear Sir/Madam,

    We are pleased to get to know that you are specialist in the field of LED
    lighting products, As a professional manufacturer and exporter
    for LED Lighting product in China, we sincerely hope to establish business
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    LED technology is always keep fast pace in recently a few years, it has
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    Some of our items maybe are suitable for your business: such as LED
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    We would like to recommend you our LED fluorescent tube series first.
    Since such items are our leading products, which we sell well recently.
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    think there should also have many similar projects ongoing in your area,
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    Please visit our website at www.tx-led.com for more details about our full
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    Look forward to discussing further details with you soon. Thanks!

    Best regards,
    Jason Zhou
    Sales manager
    Shenzhen Tianxia LED Lighting Co.,Ltd
    Email:sales@tx-led.com
    Web: http://www.tx-led.com/

    Tel: 0086 755 81920018 Mob: 086-13590170735
    Fax: 0086 755 27583461

  • RIPPED OFF commented on 06/10/2009 17:34 Report abuse

    US Samsung 46" vs Australian 46"

    US Model
    UN46B8500 US $3,599 (equiv AUS $4,090)
    local dimming LED backlight
    240Hz
    7,000,000:1

    AUS Model
    UA46B8000 AUS $4,999 (PLUS $900)
    Edge LED backlight
    200Hz
    3,000,000:1

    Don't bother with Samsung in Australia!

  • Mr Lothar commented on 06/09/2009 19:57 Report abuse

    I think you forgot to answer to the last question.

    Is the price premium for LED worth paying?

  • ****er commented on 01/09/2009 04:08 Report abuse

    Good explanation, it was exactly what I was looking for. I hope the technology for 1 LED for 1 LCD does come out, or if possible just completely LED. Thanks for your help.

  • GabrielY commented on 24/08/2009 15:59 Report abuse

    I also went for the Samsung Series 6 B CCFL and I can confirm the picture is so clear and sharp it almost looks 3D, one of the best on the market. I was going to buy the UA55B6000 LED but ended up with LA55B650 as I couldn’t tell the difference between them in store ( this is a view shared by many who compare the two ) And the Series 6 B CCFL came with Media 2.0 and Ethernet connection for Streaming movies from your PC.
    And for those of you who think LED is allot more power effient both are very close
    55:” 60000 Edgelit LED uses an operational power consumption of 220w and the
    55:” series 6 B CCFL backlit uses an operational power consumption of 250w
    for comparison the 52” series 6 A CCFL backlit uses operational power consumption of 290w and a 50” Plasma is at around 350w-500w ( Plasma TV's also double as a heater )

  • Kabul commented on 23/07/2009 14:40 Report abuse

    I had a SONY LCD 52" MODEL KDL-52W5500 & always was a SONY MAN now watching it in HD fantastic if your where viewing from a minimum 6 metres away, the non HD 576i reception with an excellent reception well forget it, in my view "very bad" example; chosting being a 100hz every movie was blurry every pixel was visible, i moved into a small 40 square apartment & it was hopeless, stressed me to the max.
    I sold it $700 less than the price i bought it from 8 months of usage that i had only used it, then along comes SAMSUNG "NOW where talking" I researched on the net & quite a few so called TV retail stores, when i asked i want to view the new LED that samsung brought out, i was constantly told oh NO we can't have free to air in our store, how would you like it if our customers where to see a example only; Harvey Norman ad on the same TV, now all the displays where shown on blue ray (obviously to get the most for sales out of the picture viewing) so after finally finding a down to earth retailer i was able to view free to air on the new samsungs & others & i decided to buy the samsung series "9" which is a LCD screen that use's LED backlighting, you can adjust everything in standard view settings gamma, tints the lot after finally it was deliver home with minor tweaking, its the best picture i have ever seen, & all the hipe about the new "B" LED series i personally think you can't beat the SAMSUNG series 9 LCD with LED BUILT in backlighting, & when the sales guy say's to you no the b series is new LED technology they are lyeing, because all your getting is an LCD TV with LED white diode lighting from the edges of the set, where the series 9 is from behind the set & allows you to tweak all and almost every viewing adjustment to suit your room lighting.
    I'm no expert but would love to here from perhaps others that are not so obsessed as i am, the SAMSUNG LA46A960D1F as i mentioned out runs the new LED any day.

  • M R Goplani commented on 06/07/2009 23:57 Report abuse

    I had a very bad exprience with Samsumg 37in LCD Tv I bought in Ahmedabad/India. Within four months of its purchase, the screen started showing horizental lines. This could not removed despite of several services rendered by the Samsung personnel so much so that my warranty period was about to be over. They could finally correct the problem by replacing the whole new screen itself. Contrary to this, I had Sony conventional TV that has never showed any problem since last 15 years. LCD or now LED technology still seem to be developed further for consumers yet.

  • LCD Winner commented on 05/07/2009 08:22 Report abuse

    We went for the Samsung Series 6 LCD CCFL after previously preferring Panasonic's thin-glass plasmas.

    The Samsung LCDs have an almost 3D presence that their (or anybody else's) plasmas do not. Only the Sony 200Hz LCD comes close, but still looks flat.

    Just a pity about Samsung's tech support (repeatedly try to avoid ANY service call) and outsourcees who seem to be clueless about LCDs.

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